1. Field of the Invention
The present invention relates to low resilience urethane foam having excellent low resilience useful as an impact energy absorbing material, a sound insulating material and a vibration damping material. The material is capable of ensuring a uniform pressure distribution to reduce fatigue and pressure gangrene, when used as a cushioning material for chairs and mattresses.
2. Description of the Prior Art
Low resilience urethane foam useful as the impact energy absorbing material, the sound insulating material, the vibration damping material and the cushioning material for chairs and mattresses is known. With the known type of low resilience urethane foam, components of the urethane foam, namely, type of polyisocyanate, functionality and hydroxyl value of polyol, are selected and formulated such that glass transition can be caused at temperature for the urethane foam to be used, i.e., at room temperature, so that low resilience can be imparted to the urethane foam by the glass transition phenomenon.
This known type urethane foam, formulated such that the glass transition can be caused at room temperature, shows excellent low resilience by the glass transition phenomenon at room temperature, but it has a disadvantage that at a temperature less than that of occurence of the glass transition, e.g., at low temperatures of 0.degree. C. or less, the urethane foam becomes glassy and its hardness increases rather drastically from that at room temperature.